Tsinghua Ma Xiongfeng's group proposes a practical multi-body entanglement detection protocol

Xiongfeng Ma's group at the Institute of Cross-Information, Tsinghua University has made important progress in the field of multi-body entanglement detection, proposing a practical and efficient entanglement detection protocol for multi-body systems.

Quantum entanglement is a fundamental concept in theoretical physics research and quantum information science, and the development of efficient entanglement detection protocols is of great significance for calibrating the reliability of large quantum devices. Traditional entanglement detection methods often have various limitations. For example, although Entanglement Witness is the most commonly used experimental scheme, its effectiveness relies heavily on a priori knowledge of the quantum state being probed. Positive Map Criterion is another theoretically powerful entanglement criterion, however, its implementation often requires quantum state cascading of extremely high experimental complexity.

Recently, researchers have proposed a moment measurement-based experimental scheme that avoids quantum state cascading and achieves a weakened version of the Positive Map Criterion. This experimental scheme requires only single copy of quantum states to be manipulated and measured, and has low experimental complexity and high detection capability. However, due to the nature of the positive mapping criterion itself, this scheme can only detect the entanglement of two-body quantum systems.

Schematic diagram of multi-body entanglement detection protocol

To solve this problem, in this work, Zhen-Huan Liu et al. introduced a new multi-body entanglement criterion, namely the indicator rotation entanglement criterion, and successfully transformed it into an experimental framework based on moment measurement. This experimental scheme has a lower experimental complexity and can probe more complex entanglement structures in many-body systems. In two-body systems, this framework gives a new two-body entanglement criterion, which greatly enhances the detection of two-body entanglement. In addition, some numerical experiments show that some key physical quantities in this framework can also be used as entanglement metrics and play an important role in the study of quantum many-body physics.

Numerical demonstration of entanglement detection capability in Ising model

The resulting paper, Detecting Entanglement in Quantum Many-body Systems via Permutation Moments, was published in Physical Review Letters [PhysRevLett.129.260501].

Corresponding author of the paper is Associate Professor Xiongfeng Ma, Institute of Cross-Information, Tsinghua University. Zhenhuan Liu, a PhD student of the Class of 2020 at the Institute of Cross-Information, Tsinghua University, is the first author of the article. Other authors include Yifan Tang, a class of 2017 undergraduate student, Hao, Ph.D., and Pengyu Liu and Shu Chen, class of 2019 undergraduate students in the Institute of Cross-Information. This project was supported by the National Natural Science Foundation of China and the National Key Research and Development Program.